It is necessary to provide a transmission line signal path when mounting high frequency semiconductors on a printed circuit board. This is especially true when using conventional, low cost plastic semiconductor packages. It is also necessary to provide adequate heat dissipation when the semiconductor is a high frequency power device.
In an effort to meet these needs, and to reduce the size of semiconductor devices, a down set, or deep down set die pad lead frame has been utilized to provide thinner packages and to eliminate the need for heat sinks and heat spreaders. In the "Deep Down set" lead frame/package, the die pad of the lead frame is down set, or up-set, and the side of the die pad opposite the side on which the semiconductor die is mounted is exposed at the external surface of the semiconductor package.